During 1997, conditions for winter crop development were favorable in our region (south of Buenos Aires Province). Oat was seeded late because of the autumn rains, but the last period of crop was good, with mild temperatures and adequate moisture. Weather was good for crop yield and for diseases too.
Rusts were, again, the principal problem for oat crops. Crown rust was important this year, and there was high incidence of stem rust.
Two cultivars released in recebt years, Máxima INTA and INIA LE Tucana (both of late maturity), were resistant to crown and stem rusts at the time of reslease. In 1997 crown rust was found on them in Castelar. Máxima had crown rust severities up to 60% while Tucana had 80% severities. The main difference between the two cultivars was that the uredinia were darker in colour in Máxima.
The cultivar Cristal INTA had crown rust levels similar to Bonaerense Payé, but the infection in Cristal began 2 days later, perhaps due to longer latent period.
We had discarded a lot of material (pure lines and population) damaged by rust, but now we have lines with good agronomic traits, good grain quality and yield; some of them have good potential.
We are conscious that the realization of the yield potential is being continually restricted by the evolution of pathogens able to overcome the resistance of the new varieties. The proximity of the cultivated areas in Argentina, Brazil and Uruguay and the increased oat acreage in Brazil are a concern to us in terms of the dynamic of the rust fungi.